Fabrication of high efficiency CuIn(Ga)Se2 thin film solar cell by of high efficiency selenization with H2Se

Effects of preparation conditions for precursors in selenization with H₂Se on film properties of CuInSe₂ and CuIn _1-xGa_xSe₂ were studied. Using a Cu/In stacked layer precursor prepared at temperature of 200 C, grain sizes for selenized CuInSe₂ films became as large as 2 μm. It was found from XRD analysis that MoSe₂ was formed at the boundary to the Mo back electrode for a selenization process using the stacked layer precursors. Formation of MoSe₂ was suppressed using a Cu-In-Se mixed compound precursor. Grain sizes for selenized CuInSe₂ films with Cu-In-Se precursors prepared at 200 C were about 1 μm. A glass/Mo/CuIn(Ga)Se₂/CdZnS/ZnO cell structure was fabricated to study the effects of the precursor on cell performances. It was found that Voc was improved for Cu-In-Se precursors as substrate temperature increased. A fill factor exceeding 0.7 was obtained using Cu-In-Se precursors prepared at 200 C. A value of Voc was improved with Ga doping near the boundary to the Mo back electrode. Using Se mixed precursors, conversion efficiencies of 12.6% and 11.7% were obtained for CuInSe₂ solar cells and CuIn_1-xGa_xSe₂ solar cells